Damage to the southwest corner of WTC 7. [Source: Arquelio Galarza]World Trade Center Building 7 (WTC 7) suffers some damage, caused by debris from the collapse of the north WTC tower, according to later official reports. [Federal Emergency Management Agency, 5/1/2002, pp. 5-16; National Institute of Standards and Technology, 11/2008, pp. 16]WTC 7 Undamaged by South Tower Collapse - WTC 7 is a 47-story office building located 370 feet north of the North Tower (WTC 1). In the final report of its investigation into WTC 7’s collapse, published in November 2008 (see November 20, 2008), the National Institute of Standards and Technology (NIST) will state that although a few windows on the lower floors of WTC 7’s south face were broken when the South Tower (WTC 2) collapsed at 9:59 a.m. (see 9:59 a.m. September 11, 2001), “None of the large pieces of debris from WTC 2 hit WTC 7, because of the large distance between the two buildings,” and there is “no evidence of structural damage to WTC 7” as a result of the South Tower’s collapse. Debris Reportedly Damages Exterior Columns - However, when the North Tower collapses (see 10:28 a.m. September 11, 2001), some fragments of debris are “forcibly ejected” from it, and travel “distances up to hundreds of meters.” According to NIST, pieces of this debris “hit WTC 7, severing six columns on floors 7 through 17 on the south face and one column on the west face near the southwest corner.” NIST will add that the debris also causes “structural damage between floor 44 and the roof,” and breaks a large number of windows on WTC 7’s south face. Building Core Undamaged - However, NIST will state, based on “photographic evidence, witness accounts, and engineering judgment, it is likely that the structural damage (steel and floor slabs) did not penetrate beyond the perimeter of the building core. At the southwest corner, the structural damage extended only about one-third of the distance from the exterior wall to the building core.” NIST will comment, “Compared to the airplane impact damage to the WTC towers, there was relatively little damage to the interior of WTC 7.” There is also “no superficial or structural damage” to WTC 7’s north and east faces. And the sprayed fire resistive material that has been applied to the building’s steel columns, girders, and beams is only damaged in the “immediate vicinity of the WTC 1 debris impact.” NIST will admit, however, that there are “uncertainties” in its accounting of the events leading up to the collapse of WTC 7, because “the remains of all the WTC buildings were disposed of before Congressional action and funding was available for [its] investigation [of the WTC collapses] to begin” (see Shortly After September 11, 2001 and September 12-October 2001). [National Institute of Standards and Technology, 8/21/2008; National Institute of Standards and Technology, 11/2008, pp. 15-16]FEMA Describes WTC 7 Damage - According to an earlier report on the collapse of WTC 7, published by the Federal Emergency Management Agency (FEMA) in May 2002 (see May 1, 2002), at that time, the “extent and severity of the resulting damage to WTC 7” when the North Tower collapses “are currently unknown.” But based on “photographic evidence and eyewitness accounts,” it is “assumed that the south side of the building was damaged to some degree.” FEMA’s report will state: “It does not appear that the collapse of WTC 1 affected the roof, or the east, west, and north elevations of WTC 7 in any significant way. However, there was damage to the southwest corner of WTC 7 at approximately floors 8 to 20, 24, 25, and 39 to 46.” The report will add: “According to firefighters’ eyewitness accounts from outside of the building, approximately floors 8-18 were damaged to some degree. Other eyewitness accounts relate that there was additional damage to the south elevation.” [Federal Emergency Management Agency, 5/1/2002, pp. 5-16, 5-20]Structural Damage Not Responsible for Collapse - WTC 7 will collapse at 5:20 p.m. this afternoon (see (5:20 p.m.) September 11, 2001). [National Institute of Standards and Technology, 8/21/2008] However, NIST will conclude that the structural damage the building suffers plays no role in causing it to come down. NIST will state, “Other than initiating the fires in WTC 7, the damage from the debris from WTC 1 had little effect on initiating the collapse of WTC 7.” [National Institute of Standards and Technology, 11/2008, pp. xxxvii] WTC 7 suffers fires on some floors, which are reportedly initiated by debris from the collapse of the North Tower (see (10:28 a.m.-5:20 p.m.) September 11, 2001). According to NIST, it is these fires, “rather than the structural damage that resulted from the impacts” of debris, which “initiated the building’s collapse.” [National Institute of Standards and Technology, 8/21/2008]

Michael Burton. [Source: PBS]Following the World Trade Center collapses, a decision is made to quickly transport the remaining structural steel to scrap yards, to be shipped abroad and melted down for reuse. Consequently, virtually all of it is disposed of before investigators trying to assess why the WTC collapsed can examine it. Michael Burton and other officials at the Department of Design and Construction—the New York City agency overseeing the cleanup operation (see (September 11, 2001-May 2002))—are responsible for making this decision. Burton clears it with Richard Tomasetti of Thornton-Tomasetti Engineers, the prime consultant on the cleanup job. However, referring to the subsequent WTC investigation by the National Institute of Standards and Technology (see August 21, 2002), Tomasetti will later admit that had he known the direction that investigations into the collapses would take, he would have taken a different stand. [Langewiesche, 2002, pp. 30; Glanz and Lipton, 2004, pp. 330 and 396] Authors and New York Times reporters James Glanz and Eric Lipton write that Michael Burton, “who had become the effective czar for the cleanup job, had made it clear that he cared very little about engineering subtleties like the question of why the towers first stood, then collapsed on September 11. ‘We know why they fell,’ he said. ‘Because they flew two planes into the towers.’ But he was deeply immersed in the details of hauling steel out of the debris pile.” [Glanz and Lipton, 2004, pp. 299] Much of the WTC steel will be shipped to India, China, and other Asian countries for recycling (see September 12-October 2001).

A structural engineer who was a member of the team assembled by the American Society of Civil Engineers to investigate the World Trade Center site after 9/11 complains about the decision to rapidly destroy the remaining structural steel from the collapsed WTC buildings. Dr. Abolhassan Astaneh-Asl is a professor of civil and environmental engineering at the University of California at Berkeley, and specializes in studying structural damage done by earthquakes and terrorist bombings. [Chronicle of Higher Education, 12/7/2001; CBS News, 3/11/2002; Associated Press, 9/6/2002] He had come to New York a week after 9/11 to examine the collapsed towers, hoping to gain an understanding of how they had come down (see September 19-October 2001). [New York Times, 10/2/2001; US Congress. House. Committee on Science, 3/6/2002] However, New York City officials had decided early on to quickly transport the remaining structural steel to scrap yards, to be shipped abroad and melted down for reuse (see Shortly After September 11, 2001). As CBS News now reports, “As a result, Astaneh has almost certainly missed seeing crucial pieces before they were cut up and sent overseas.” Astaneh-Asl complains: “When there is a car accident and two people are killed, you keep the car until the trial is over. If a plane crashes, not only do you keep the plane, but you assemble all the pieces, take it to a hangar, and put it together. That’s only for 200, 300 people, when they die. In this case you had 3,000 people dead.” He says: “My wish was that we had spent whatever it takes, maybe $50 million, $100 million, and maybe two years, get all this steel, carry it to a lot. Instead of recycling it, put it horizontally, and assemble it. You have maybe 200 engineers, not just myself running around trying to figure out what’s going on. After all, this is a crime scene and you have to figure out exactly what happened for this crime, and learn from it.” However, he adds, “My wish is not what happens.” [CBS News, 3/12/2002] Astaneh-Asl previously told the New York Times that the scrap steel from the WTC was “worth only a few million dollars, a tiny fraction of the billions of dollars the cleanup will cost.” Yet the knowledge that could be gained from it “could save lives in a future disaster.” [New York Times, 10/2/2001]

The National Institute of Standards and Technology (NIST)—an agency of the US Commerce Department’s Technology Administration—announces details of its forthcoming investigation into the collapses of the World Trade Center Twin Towers and Building 7 on 9/11. The NIST investigation aims “to investigate the building construction, the materials used, and the technical conditions that contributed to the outcome of the World Trade Center (WTC) disaster.” It also aims to examine the activities of building occupants and emergency responders on 9/11, studying such issues as emergency communications within the WTC, the movement of people during the evacuations, and issues around persons with disabilities. Leading technical experts from industry, academia, and other laboratories, alongside NIST’s own expert staff, will participate in the investigation. Expert professionals from the private sector will also be involved. Glenn Corbett, a fire science professor at John Jay College, says, “This is going to be the most extensive building disaster investigation ever performed.” [Associated Press, 8/21/2002; National Institute of Standards and Technology, 8/21/2002; National Institute of Standards and Technology, 8/3/2005] The investigation is formally authorized in October 2002, when the National Construction Safety Team Act is signed into law. The act, which gives NIST authorization to investigate major building failures in the US, is written largely as a result of the World Trade Center collapses. [National Institute of Standards and Technology, 10/2/2002; New York Times, 5/8/2003] NIST’s investigation is originally proposed to last two years, with a budget of $16 million. [National Institute of Standards and Technology, 8/21/2002] However, it eventually will last three years, with its final report into the collapses of the Twin Towers being released in October 2005 (see October 26, 2005). A previous analysis of the WTC collapses conducted by FEMA and the American Society of Civil Engineers (ASCE) was completed earlier in 2002 (see May 1, 2002), but this had a budget of just $1.1 million. By the time NIST starts its investigation, much of the crucial steel debris from the WTC collapses has already been destroyed (see September 12-October 2001). They later refer to there being a “scarcity of physical evidence that is typically available in place for reconstruction of a disaster.” [National Institute of Standards and Technology, 9/2005, pp. xxxvi]

The National Institute of Standards and Technology (NIST) publishes a fact sheet responding to 14 “frequently asked questions” about its investigation into the collapse of the Twin Towers on September 11. Some of the key questions and answers are as follows: Regarding the question, “Why was the collapse of WTC 1 and 2 not arrested by the intact structure below the floors where columns first began to buckle?” NIST replies, “The vertical capacity of the connections supporting an intact floor below the level of collapse was adequate to carry the load of 11 additional floors if the load was applied gradually and 6 additional floors if the load was applied suddenly (as was the case).” As the number of floors above the points where the collapses initiated exceeded six (12 in the case of the North Tower, 29 for the South), NIST says, “[T]he floors below the level of collapse initiation were unable to resist the suddenly applied gravitational load from the upper floors of the buildings.” In answer to the question of “Why was physical evidence not collected immediately following the collapse of the WTC towers,” NIST says, “In the initial days and weeks following the WTC disaster, the emphasis was on rescue and later on recovery, necessitating the removal of steel and disturbing the collapse site.” It adds, “NIST did not receive the legal authority to collect and preserve physical evidence from a disaster/failure site until the National Construction Safety Team Act became law in October 2002.” The decision to rapidly scrap the remaining steel from the WTC was made shortly after 9/11 (see Shortly After September 11, 2001), but the destruction of this steel was strongly protested by some within the engineering and firefighting communities (see December 25, 2001 and January 4, 2002). In response to a question about why it did not use its subpoena authority during its investigation, NIST states that its “experience during the investigation was that it was able to obtain all essential documentary and visual evidence without the need to invoke subpoena authority.” In answer to the question, “Why didn’t NIST fully model the collapse initiation and propagation of WTC towers?” NIST says, “Once the collapse had begun, the propagation of the collapse was readily explained without the same complexity of modeling” as was used to determine the sequence of events leading up to the collapse initiation. During its investigation, NIST had selected several variables for its computer simulations, and then experimented with different possible values (see (October 2002-October 2005)). But it has been asked: “Why didn’t NIST consider the ‘base’ and ‘less severe’ cases throughout its analysis of the WTC towers? What was the technical basis for selecting only the ‘more severe’ case for its analyses?” Its answer is that, “Of the three [possible values], the more severe case resulted in the closest agreement with the visual and physical evidence.” [National Institute of Standards and Technology, 12/14/2007]NIST published its final report on the Twin Towers collapse in October 2005 (see October 26, 2005). It released an earlier fact sheet answering previous “frequently asked questions” in August 2006 (see August 30, 2006). [National Institute of Standards and Technology, 8/30/2006]

After the National Institute of Standards and Technology (NIST) announces the results of its investigation into the collapse of World Trade Center Building 7, some critics dispute its explanation for the collapse and question its apparent debunking of claims that explosives were used to demolish the building. The 47-story tower collapsed late in the afternoon of 9/11, even though no plane hit it (see (5:20 p.m.) September 11, 2001). Some have argued that fire and the falling debris from the Twin Towers’ collapses should not have brought down such a large steel and concrete structure. [Associated Press, 8/21/2008]NIST Lacks 'the Expertise on Explosives' - James Quintiere, a professor of fire protection engineering at the University of Maryland who previously worked as the chief of NIST’s fire science and engineering division, says that NIST does not “have the expertise on explosives, so I don’t know how they came to that conclusion,” that explosives did not cause the collapse. However, Quintiere says he never personally believed explosives were involved. [Los Angeles Times, 8/22/2008] Richard Gage, a California architect and leader of a group called Architects and Engineers for 9/11 Truth, complains, “How much longer do we have to endure the cover-up of how Building 7 was destroyed?” The New York Times points out that “the collapse of 7 World Trade Center—home at the time to branch offices of the Central Intelligence Agency, the Secret Service, and the Giuliani administration’s emergency operations center—is cited in hundreds of Web sites and books as perhaps the most compelling evidence that an insider secretly planted explosives, intentionally destroying the tower.” [New York Times, 8/21/2008]NIST Presentation - At a presentation of its findings earlier in the day, NIST announced that, in its three-year study of the collapse, it found no evidence showing explosives were used to bring the building down. [National Institute of Standards and Technology, 8/21/2008; National Institute of Standards and Technology, 8/21/2008] During his summary of the findings of NIST’s WTC 7 investigation (see August 21, 2008), lead investigator Shyam Sunder said, “We did not find any evidence that explosives were used to bring the building down.” [National Institute of Standards and Technology, 8/21/2008]'No Witness Reports' of Loud Explosions - In the draft version of its final report on the collapse, which is released on this day (see August 21, 2008), NIST explains: “Blast from the smallest charge capable of failing a critical column… would have resulted in a sound level of 130 dB to 140 dB at a distance of at least half a mile if unobstructed by surrounding buildings.… This sound level is consistent with standing next to a jet plane engine and more than ten times louder than being in front of the speakers at a rock concert. There were no witness reports of such a loud noise, nor was such a noise heard on the audio tracks of video recordings of the WTC 7 collapse.” [National Institute of Standards and Technology, 8/2008, pp. 44-45 ]NIST Rules out Thermite - Skeptics have argued that an incendiary material called thermite was used to bring down WTC 7 (see August 4, 2008), and this would not necessarily have created such a loud explosive boom. [New York Times, 8/21/2008] But in a fact sheet published on this day, NIST responds: “To apply thermite to a large steel column, approximately 0.13 lb of thermite would be needed to heat and melt each pound of steel. For a steel column that weighs approximately 1,000 lbs. per foot, at least 100 lbs. of thermite would need to be placed around the column, ignited, and remain in contact with the vertical steel surface as the thermite reaction took place. This is for one column… presumably, more than one column would have been prepared with thermite, if this approach were to be used. It is unlikely that 100 lbs. of thermite, or more, could have been carried into WTC 7 and placed around columns without being detected, either prior to Sept. 11 or during that day.” [National Institute of Standards and Technology, 8/21/2008] Sunder says that investigators therefore decided not to use their computer model to evaluate whether a thermite-fueled fire might have brought down WTC 7. Pointing to the omission, one skeptic says, “It is very difficult to find what you are not looking for.” [New York Times, 8/21/2008] In a 2006 fact sheet, NIST in fact admitted it “did not test for the residue” of explosives or thermite in the remaining structural steel from the WTC collapses (see August 30, 2006). [National Institute of Standards and Technology, 8/30/2006] And, as the New York Times notes, “Adding to the suspicion is the fact that in the rush to clean up the site, almost all of the steel remains of the tower were disposed of, leaving investigators in later years with little forensic evidence” (see Shortly After September 11, 2001 and September 12-October 2001). [New York Times, 8/21/2008]Extensive Preparations for Demolition - NIST’s new fact sheet also points out: “For [WTC 7] to have been prepared for intentional demolition, walls and/or column enclosures and fireproofing would have to be removed and replaced without being detected. Preparing a column includes steps such as cutting sections with torches, which produces noxious and odorous fumes. Intentional demolition usually requires applying explosive charges to most, if not all, interior columns, not just one or a limited set of columns in a building.” [National Institute of Standards and Technology, 8/21/2008]

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